The Free Scalar as a Thermal Envelope for Three-Dimensional CFTs
Abstract
We conjecture that every unitary three-dimensional conformal field theory obeys cS/CT≤16πζ(3), where s=cST2 is the thermal entropy density and CT the stress-tensor two-point coefficient, with equality for free scalars. We embed this in a stronger conjecture: on S1× H2, the CT-normalized hyperbolic heat capacity is bounded above by that of the free scalar for all T≥(2πR)−1. Near the conformal temperature, for theories smooth from the high-temperature side and without boundary terms in the modular Hamiltonian, the heat-capacity bound follows from conformal-collider positivity. We test the conjectures in free, interacting large-N, and holographic theories. Monte Carlo data for the three-dimensional Ising and O(N) models also obey the flat-space bound.
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BibTeX
@misc{herzog2026free,
title = {{The Free Scalar as a Thermal Envelope for Three-Dimensional CFTs}},
author = {Christopher P. Herzog and Andreas Stergiou},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.33179},
eprint = {2610.33179},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.33179},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - The Free Scalar as a Thermal Envelope for Three-Dimensional CFTs
AU - Christopher P. Herzog
AU - Andreas Stergiou
PY - 2026
DA - 2026/10/23
PB - arXiv
DO - 10.48550/arxiv.2610.33179
UR - https://arxiv.org/abs/2610.33179
AB - We conjecture that every unitary three-dimensional conformal field theory obeys c_S/C_T≤16πζ(3), where s=c_ST^2 is the thermal entropy density and C_T the stress-tensor two-point coefficient, with equality for free scalars. We embed this in a stronger conjecture: on S^1× H^2, the C_T-normalized hyperbolic heat capacity is bounded above by that of the free scalar for all T≥(2πR)^−1. Near the conformal temperature, for theories smooth from the high-temperature side and without boundary terms in the modular Hamiltonian, the heat-capacity bound follows from conformal-collider positivity. We test the conjectures in free, interacting large-N, and holographic theories. Monte Carlo data for the three-dimensional Ising and O(N) models also obey the flat-space bound.
ER -